Dynamic configuration of radio link protocol in a telecommunications system

ABSTRACT

A method and apparatus for dynamically configuring parameters of the radio link protocol layer in a telecommunications system. The method and apparatus allows dynamic configuration of the radio link protocol layer in order to optimize parameters for use with a particular data service. In an embodiment of the invention, radio link protocol control frames used for connection initialization include RLP parameter data. The RLP parameter data is exchanged between two communicating transceiving devices during connection initialization, and is used in each transceiving device to configure subsequently transmitted RLP data frames and transmit retransmission requests accordingly.

FIELD OF THE INVENTION

This invention relates to telecommunications systems, and, moreparticularly, to a method and apparatus for dynamically configuring aradio link protocol (RLP) for a telecommunications system.

BACKGROUND OF THE INVENTION

Major cellular system types include those operating according to theGlobal Services for Mobile(GSM)Standard, the TIA/EIA/IS-95 MobileStation-Base Station compatibility Standard for Dual Mode Wide BandSpread Spectrum Cellular System, the TIA/EIA/IS-136 Mobile Station-BaseStation Compatibility Standard, and the TIA/EIA 553 AnalogStandard(AMPS/TACS). Other major cellular systems include thoseoperating in the personal communications system(PCS) band according tothe IS-95 based ANSI-J-STD-008 1.8-2.0 Ghz standard or, those operatingaccording to the GSM based PCS1900(1900 Mhz frequency range) standard.

Currently, each of the major cellular systems standards bodies areimplementing data services into their digital cellular specifications. Apacket data service specification has been finalized for GSM and, packetdata service specifications compatible with the IS-95 and IS-136standards are being prepared. Another example of a data service is theTIA/EIA IS-99 Data Services Option Standard for Wideband Spread SpectrumDigital Cellular System(IS-99). IS-99 defines a connection based packetservice for IS-95-A based networks. The IS-99 system provides a standardfor asynchronous data service (Service Option 4) and digital Group-3facsimile service (Service Option 5).

In an IS-99 based system, a radio link protocol (RLP) is utilized toprovide an octet stream service over IS-95-A forward and reverse trafficchannels. Each octet comprises 8 bits of digital data. The octet streamservice carries the variable length data packets of the point to pointprotocol layer. The RLP divides the point to point protocol packets intoIS-95-A traffic channel frames for transmission. There is no directrelationship between point to point protocol packets and IS-95-A frames.A large packet may span several IS-95-A traffic channel frames, or asingle traffic channel frame may include all or part of several point topoint packets. The RLP does not take the higher level traffic channelframing into account, but operates on a featureless octet stream,delivering the octets in the order received from the point to pointlayer. The data may be transmitted on the traffic channel as primarytraffic, or, for example, along with speech, as secondary traffic. Datamay also be transmitted in a signaling subchannel. IS-95 multiplexoption 1 may be used at full rate, half rate and eighth rate for primarytraffic and at rate 1, rate 7/8, rate 3/4, and rate 1/2, for secondarytraffic.

The RLP utilizes RLP control frames to control the transmission of dataand RLP data frames for the transmission of data at the RLP level.

The format of RLP control and data frames is defined so that each RLPframe includes a 8-bit sequence number field (SEQ). Each RLP data frameSEQ field contains the sequence number of that particular data frame.The sequence numbers are used to identify each received data frame andallow determination of data frames that have not been received. The RLPcontrol frame SEQ field is not used to indicate the sequence number ofthe control frame, but contains the next data frame sequence number, toallow quick detection of erased data frames.

In addition to the SEQ field, each RLP data frame includes a number ofdata bits, with up to a maximum number of data bits allowed for eachframe. The maximum number of data bits allowed in a data frame dependsupon the IS-95 multiplex subchannel used. For example, for primarytraffic on the traffic channel, using multiplex option 1 at IS-95 fullrate, the maximum number of data bits allowed is 152, and, for primarytraffic on the traffic channel, using multiplex option 2 at IS-95 halfrate, the maximum number of data bits allowed is 64. When less than themaximum number of bits are transmitted in a frame, padding is used tofill out the data field to 152 bits. Each RLP data frame also includes aRLP frame type (CTL) field, and a data length (LEN) field. The LEN fieldindicates the length of the data in the frame in octets. For unsegmenteddata frames, the CTL frame is one bit and is set to 0. For segmenteddata frames, the CTL frame contains 4 bits and can be set to indicatewhether the data in the frame includes the first LEN octets, the nextLEN octets, or, the last LEN octets of the unsegmented data frame.

The RLP control frame may function as a negative acknowledgement (NAK)RLP control frame. A (NAK) RLP control frame includes a 4 bit frame type(CTL) field, a four bit length (LEN) field, an 8 bit FIRST field, an 8bit LAST field, a reserved field (RSVD), a frame check sequence field(FCS) and padding. An RLP control frame having the frame type field setto indicate negative acknowledgement (NAK) may then be used to requestretransmission of a particular data frame, or, a particular sequence ofdata frames. For example, a mobile station expecting a data frame havinga particular sequence number, would transmit a NAK control frame to thebase station if the mobile determined that the data frame was missed.The FIRST and LAST fields of the RLP NAK control frame are used toindicate the particular data frame, or, sequence (indicated as a rangebeginning at the sequence number indicated by the FIRST field and endingat the sequence number indicated by the LAST field) of data frames thatare requested to be retransmitted. In IS-99, the number of requests forretransmission of a data frame is a set number and the initiation of therequests for retransmission is controlled by a NAK retransmission timer.When RLP frames are carried as primary or secondary traffic, theretransmission timer is implemented as a frame counter. When RLP framesare carried in the signaling subchannel, the retransmission timer isimplemented as a timer having a duration equal to a predetermined value,T1m, that is defined in Appendix D of IS-95-A. The NAK retransmissioncounter for a data frame is started upon the first transmission of a NAKRLP control frame requesting retransmission of that data frame.

If the data frame has not arrived at the receiver when its NAKretransmission timer expires, the receiver sends a second NAK controlframe requesting retransmission of that data frame. This NAK controlframe is transmitted twice. The NAK retransmission timer for this dataframe is then restarted. If the data frame has not arrived at thereceiver when its NAK retransmission timer has expired twice, thereceiver sends a third NAK control frame requesting retransmission ofthat data frame. Each NAK control frame transmitted as the result of aretransmission timer expiring a second time is transmitted three times.

A NAK abort timer is then started in the receiver upon transmission ofthe third NAK control frame. The NAK abort timer is implemented, andexpires, identically to the NAK retransmission timer. If the data framehas not arrived at the receiver when its NAK abort timer has expired,the NAK is aborted and no further NAK control frames are transmitted forthat data frame.

The IS-99 NAK scheme results in a maximum number of three retransmissionrequests, that include a maximum number of six NAK RLP control frames,being transmitted for a particular unreceived data frame.

As cellular telecommunications systems evolve, various high speed data(HSD) service options will be implemented into the different cellularsystem standards. For example, several HSD options are being consideredfor implementation into the IS-95-A standard. These HSD options mayinclude IS-95-A based systems having the capability to transmit data atrates of up to 78.8 kbps. Use of any of these options in IS-95-A willincrease the range of services and applications that can be supported.For an IS-99 based system, an increase in the number of services andapplications that the system may support will require that the systemsupport data services having different bandwidth, delay sensitivity andquality of service requirements (QoS).

Different bandwidth, delay sensitivity and quality of servicerequirements may require different bit error rate(BER), and, delayrequirements. A fixed frame header and fixed NAK retransmissionprocedure such as that of IS-99 may not be optimally configured forcertain data services that must be supported. For example, it may bethat a service with low QoS requirements (high BER allowed) mayexperience large delays from a NAK retransmission procedure in a systemhaving a predetermined number of retransmissions, when it is not reallynecessary to retransmit missing data frames the predetermined number oftimes in order to provide acceptable service. Another example ofnon-optimization in a data packet service using a fixed frame header,such as that of IS-99, could occur if a service required high bandwidthand included large numbers of sequenced data frames to be transmitted ashigh speed data. This service may use long data sequences having anumber of data frames greater than X, which is the maximum numberindicated by the full SEQ field of the fixed frame header. In this case,the count in the SEQ field would have to be restarted before a long datasequence was finished. Restarting the count in the sequence field mayrequire more complicated processing of the transmitted and received datathan having each frame in the data sequence numbered sequentially.Additionally, if a data service uses a shorter data sequence having anumber of data frames less than the maximum number indicated by the SEQfield, this may be nonoptimal because bits reserved for the SEQ field gounused in each data frame, when these bits could be used to carry data.

OBJECTS OF THE INVENTION

It is a first object of this invention to provide an efficient methodand apparatus for transmitting data in a telecommunications network thatovercomes the foregoing and other problems.

Another object of this invention is to provide a method and apparatusfor dynamically configuring a radio link protocol for a particular typeof data service in which the radio link protocol is to be used.

Another object of this invention is to provide a method and apparatusfor dynamically configuring the number of bits to be included in asequence numbering field of a radio link protocol frame.

A further object of this invention is to provide a method and apparatusfor dynamically configuring the value of a retransmission count used tocontrol the number of negative acknowledgements to be sent from anintended receiver, when a expected radio link protocol frame is notreceived at the intended receiver.

SUMMARY OF THE INVENTION

The foregoing and other problems are overcome and the objects of theinvention are realized by methods and apparatus in accordance withembodiments of this invention.

The present invention provides a method and apparatus for dynamicallyconfiguring parameters of the radio link protocol layer in atelecommunications system. The method and apparatus allows dynamicconfiguration of the radio link protocol layer in order to optimizeparameters for use with a particular data service. The radio linkprotocol parameters may include parameters specifying the configurationof radio link protocol frames and/or other parameters controlling radiolink protocol transmissions. The method and apparatus utilizes aconfiguration procedure that is performed prior to initiation of thedata service between two communicating transceiving devices. Theconfiguration may also be performed to reset parameters of the radiolink protocol layer during ongoing data service.

During the configuration procedure, parameters may be agreed upon forthe radio link protocol to be used in each direction on the radio linkbetween the transceiving devices. The invention provides an advantageover telecommunications systems that use fixed frame headers, and thatconsequently may require larger amounts of processing when undersizedfields have to be reused in the transmission, or that waste potentialavailable bandwidth by under-utilizing the bits of oversized fields. Theinvention also prevents delays or quality of service degradations thatare caused by the retransmission of unreceived data frames a number oftimes that is either greater or less than is required by a particulardata service.

In an embodiment of the invention, a radio link protocol control frameused for configuring a link setup in a data service between twocommunicating transceiving devices includes a sequence size field thatindicates a bit length required for a frame sequence number(SEQ) fieldto be used in subsequent radio link protocol data frames and radio linkprotocol control frames. The radio link protocol control frame used forlink setup may also include a retransmission field indicating the numberof retransmission requests allowed for particular data frames in thedata service that have been transmitted but not received. The radio linkcontrol frame is used during the initialization or the reset of thelinks to be used. Radio link control frames may be exchanged between thetransceiving devices in order to configure radio link protocolparameters such as the size of the sequence number field and theretransmission request count for each direction on the link.

In order to configure radio link protocol parameters duringinitialization or to reset the radio link protocol parameters during anongoing data service, a first transceiving device of the twocommunicating transceiving devices transmits a first RLP control frameto the second transceiving device. The first RLP control frame includesa sequence size field, a retransmission request field, and a fieldindicating that the frame includes the sequence size field andretransmission field. The first RLP control frame indicates to thesecond transceiving device that it is going to transmit frames to thesecond transceiving device that includes a (SEQ) field containing thenumber of bits that is indicated in the sequence size field of the firstRLP control frame. The first RLP control frame also indicates to thesecond transceiving device in the retransmission request field themaximum number of retransmission requests allowed from the secondtransceiving device, for unreceived data frames transmitted on the linkfrom the first transceiving device to the second transceiving device.The second transceiving device receives the first RLP control frame andconfigures itself to receive data on the link from the firsttransceiving device to the second transceiving device and transmitsretransmission requests for data frames unreceived on that linkaccording to the information received in the first RLP control frame.

The second transceiving device then transmits a second RLP control frameto the first transceiving device. The second RLP control frame alsoincludes a sequence size field, a retransmission field, and a fieldindicating that the frame includes the sequence size field andretransmission field. The second RLP control frame also includes anindication that the second frame is transmitted in response to receivingthe first RLP control frame. The second RLP control frame indicates tothe first transceiving device that the second transceiving device is totransmit frames having a sequence number (SEQ) field containing thenumber of bits that is indicated in the sequence size field. The secondRLP control frame also indicates to the first transceiving device, inthe retransmission field, a maximum number of retransmission requestsallowed from the first transceiving device for unreceived data framestransmitted on the link from the second transceiving device to the firsttransceiving device. After receiving the second RLP control frame, thefirst transceiving device configures itself to receive data on the linkfrom the second transceiving device to the first transceiving device andtransmit retransmission requests for data frames unreceived on that linkaccording to the information in the second RLP control frame. The firsttransceiving device then sends a control frame to the secondtransceiving device in acknowledgement. The first and secondtransceiving devices then transmit and receive data and control framesaccordingly.

BRIEF DESCRIPTION OF THE DRAWINGS

The above set forth and other features of the invention are made moreapparent in the ensuing Detailed Description of the Invention when readin conjunction with the attached Drawings, wherein:

FIG. 1 is a block diagram of a cellular terminal that is suitable forpracticing this invention;

FIG. 2 depicts the terminal of FIG., 1 in communication with a CDMAcellular network;

FIGS. 3A, 3B and 3C are a pictorial representation of a radio linkprotocol (RLP) control frame structure employed, in accordance with theinvention, by a mobile station and base station to configure the RLP fora communications link between the mobile station and base station;

FIG. 4 is a flow diagram illustrating the radio link protocol (RLP)configuration procedure according to the invention, the flow diagrambeing presented as FIGS. 4A, 4B, and 4C.

DETAILED DESCRIPTION OF THE INVENTION

Referring now to FIGS. 1 and 2, therein are illustrated a wireless userterminal or mobile station (MS) 10 and cellular network 32, that issuitable for practicing this invention. The mobile station 10 includesan antenna 12 for transmitting signals to and, for receiving signalsfrom a base site or base station (BS) 30. The (BS) 30 is a part ofcellular network 32 that includes a mobile switching center (MSC) 34.The MSC 34 provides a connection to landline trunks when the MS 10 isinvolved in a call.

The MS 10 includes a modulator (MOD) 14A, a transmitter 14, a receiver16, a demodulator (DEMOD) 16A, and a controller 18 that provides signalsto and receives signals from modulator 14A and demodulator 16A,respectively. These signals may include signaling information, and alsospeech, data and/or packet data transmitted between MS 10 and BS 30 inaccordance with the air interface standard of the applicable cellularsystem.

Controller 18 may be comprised of a digital signal processor device, amicroprocessor device, and various analog to digital converters, digitalto analog converters, and other support circuits. The control and signalprocessing functions of the mobile station are allocated between thesedevices according to their respective capabilities. MS 10 also includesa user interface comprised of a conventional earphone or speaker 17, aconventional microphone 19, a display 20, and a user input device,typically a keypad 22, all of which are coupled to the controller 18.The keypad 22 includes the conventional numeric (0-9) and related keys(#,*) 22a, and other keys 22b used for operating the mobile station 10.These other keys 22b may include, by example, a SEND key, various menuscrolling and soft keys, and a PWR key. The mobile station 10 may alsoinclude a battery 26 for powering the various circuits that are requiredto operate the mobile station.

The mobile station 10 also includes various memories, shown collectivelyas the memory 24, wherein are stored a plurality of constants andvariables that are used by the controller 18 during the operation of themobile station. For example, the memory 24 may store the values ofvarious cellular system parameters and the number assignment module(NAM). An operating program for controlling the operation of controller18 is also stored in the memory 24 (typically in a ROM device). Thememory 24 may also store data prior to transmission or after reception.The memory 24 also includes routines for implementing the method ofradio link protocol configuration according to the described embodimentof the invention.

Mobile station 10 may also function as a data terminal for transmittingor receiving data. As such, in this case MS 10 may be connected to aportable computer or a fax machine through a suitable data port (DP) 28.

BS 30 also includes the necessary transmitters and receivers to allowsignal exchange with MS 10. Controllers, processors and associatedmemories that may be located in BS 30 or MSC 34 provide control of theBS 30 and MSC 34, and implement routines for the method and apparatus ofradio link protocol configuration according to the described embodimentof the invention.

In the embodiment of this invention the MS 10 and the network 32 operateusing a direct sequence, code division multiple access (DS-CDMA) systemthat is based on the IS-95A system standard. The network may operate inthe 800 Mhz frequency range according to IS-95A standard, or, in the1.8-2.0 Ghz range according to the IS-95 based ANSI-JSTD-008 standard.The network may provide a service option feature based on the IS-99standard and, may also use high speed data techniques that have beenproposed for CDMA based systems to provide higher speed datatransmission than is presently provided by the present IS-95A and IS-99standards.

For example, more than one Walsh channel may be used on the forward linkto provide high speed data, by simultaneously carrying separate datathat belongs to the same user transmission. On the reverse link,multiplexed channels may be used to increase the data rate. In thismethod serial data is input to a transmitter/modulator at an input datarate which is higher than the base data transmission rate. The serialdata is received over a time period having a duration equal to theduration of the 20 millisecond IS-95 transmission frame anddemultiplexed into a plurality of sets of input data. Each of theplurality of sets of input data is then processed in one of a pluralityof subchannels using a system channel encoding and interleaving schemeto generate a plurality of sets of processed data. A output serial datastream is then generated by multiplexing the plurality of sets ofprocessed data from the subchannels together. The serial output streamis generated so that the originally received serial data included in theserial output data stream, is generated at the input data rate. Theserial output data stream is then spread to generate at least one spreaddata stream and transmitted on the channel during a second time periodhaving a duration equal to the duration of the IS-95 transmission frame,so that the serial data included in the at least one spread data streamis transmitted at the input data rate.

In accordance with the invention, the IS-99 RLP data and control framesare modified, so that the frames may be used in a RLP configurationprocess that is performed upon initiation or reset of a data service.Referring now to FIGS. 3A, 3B and 3C, therein are illustrated structuresfor a RLP control frame 300, an unsegmented RLP data frame 320, and asegmented RLP data frame 340, respectively, that are employed by amobile station and base station to implement a dynamic RLP protocol inaccordance with the invention. RLP control frame 300 includes RLP frametype (CTL) field 302, sequence number (SEQ) field 304, reserved octetlength (LEN) field 306, sequence size/first sequence number (SES/FIRST)field 308, retransmission number/last sequence number (RETN/LAST) field310, reserved (RSVD) field 312, frame check sequence (FCS) field 314,and padding 316. Unsegmented RLP data frame 320 includes CTL field 322,SEQ field 324, LEN field 326, RSVD field 328, DATA field 330 and padding332. Segmented RLP data frame 340 includes CTL field 342, SEQ field 344,LEN field 346, RSVD field 348, DATA field 350 and padding 352.

In order to implement the embodiment of the invention, the RLP controland data frame structure is modified from the IS-99 structure, so thatthe positions of the CTL and SEQ fields in the RLP control and dataframes have been exchanged as compared to IS-99, and, so that the RLPdata frame SEQ fields 324 and 344 are modified to be variable in length.In the RLP control frames, the FIRST and LAST fields have been modifiedto provide the SES and RETN functions, respectively. In the unsegmentedand segmented RLP data frames 320 and 340, the RSVD fields 328 and 348,respectively, have been added to account for the variable length of theSEQ field.

The CTL field 302 indicates the RLP control frame type. CTL field 302indicates whether the RLP control frame is a negative acknowledgement(NAK) control frame, SYNC control frame, an acknowledgement (ACK)control frame, or a synchronization/acknowledegment (SYNC/ACK) controlframe. LEN field 306 indicates the length of RSVD field in octets andFCS field 314 provides a frame check sequence that provides an errorcheck on the control frame 300. For the unsegmented data frame 320, theCTL field 322 may be one bit and may be set to 0. For the segmented dataframe 340, CTL field 342 indicates whether the data frame 340 containsthe first, last, or a middle segment of the segmented data. LEN fields326 and 346 indicate the length of the DATA field 330 and 340,respectively.

The memory associated with the controller in each of the MS 10 and BS 30includes values stored for V1(ses), V1(retn), V2(ses) and V2(retn).V1(ses) is the value, in bits for the size of the SEQ fields 304, 324 or344, when a RLP frame is transmitted on the forward link, and V1(retn)is the maximum number of retransmission requests allowed on the reverselink for an unreceived data frame that was transmitted on the forwardlink. V2(ses) is the value for the size of the SEQ fields 304, 324 or344 when an RLP frame is transmit on the reverse link and V2(retn) isthe maximum number of retransmission requests allowed on the forwardlink for an unreceived data frame that was transmitted on the reverselink. V1(ses) and V1(retn) are determined in BS 30, and V2(ses) andV2(retn) are determined in MS 10. These values may be determined by thecontrollers within MS 10 and BS 30 according to information on the dataservice to be used, for example, based on data rate, number of frames,quality of service, etc., or, the appropriate values may be input to MS10 and BS 30 from the termination points of the data link, for example,from a fax machine connected to MS 10. The values are then exchangedduring radio link protocol configuration so that each of MS 10 and BS 30has the protocol information for both forward and reverse links. Thecontrollers in MS 10 and BS 30 are configured to format and transmit RLPframes, transmit retransmission requests, and receive RLP framesaccording to these values.

Referring now to FIG. 4, therein is a flow diagram illustrating theradio link protocol configuration procedure according to the invention.In the embodiment of the invention, the procedure of FIG. 4 may be usedupon initiation of a data service between MS 10 and network 32 of FIG.2. The procedure of FIG. 4 may also be used to reset the RLP protocolparameters for a data service after the data service has been initiated.Although described in the context of a mobile station originatedsynchronization procedure, it should be realized that the process issymmetrical, and that the base station 30 can originate the procedure aswell.

The process begins at step 402. The configuration is implemented,preferably, so that the configuration process is embedded in theconnection initialization process. The messages exchanged perform thedual function of initializing the connection and configuring the dynamicRLP. At step 404, the RLP configuration process begins using themodified RLP control frames in accordance with this invention. A SYNCcontrol frame (CTL=1101) is formatted within MS 10 having the SES/FIRSTfield 308 set to the value of X1, and the RETN/LAST field 310 set to thevalue of Y1. At step 406, MS 10 then transmits the SYNC control frame toBS 30. At step 408, a determination is made within BS 30 as to whetheror not SES/FIRST field 308 of the SYNC control frame is set to 0, i.e,whether X1 has been assigned the value of 0. If the SES/FIRST field 308is set to 0, the process moves to step 412. At step 412, V₁ (ses) is setto the default value for the sequence size in bits of the SEQ field322/344 to be used on the reverse link for RLP data frames. In theembodiment of the invention, the default value may be set to 8. Theprocess next moves to step 416.

If, however, at step 408, it is determined that SES/FIRST field 308 isnot set to 0, the process moves to step 410. At step 410, adetermination is made within BS 30 as to whether or not the value of X1in the SES/FIRST field 308 is a valid value. To be considered a validvalue, the value of SES/FIRST field 308 must be a value within thepredetermined range of from 8 to 12. If the value of SES/FIRST field 308is not valid, the process moves to the block labeled as "A". In thiscase the entity detecting the invalid condition restarts theinitialization procedure. That is, and by example, if the base station30 detects an invalid parameter at Block 410, the base station 30 sendsa SYNC frame to the mobile station 10. Since the mobile station 10 isexpecting a SYNC/ACK frame, the receipt of the SYNC frame indicates tothe mobile station 10 that the base station 30 found one or moreparameters objectionable, and was replying with base station preferredparameters.

If however, the value of SES/FIRST field 308 is valid, the process movesto step 414. At step 414, V1(ses) is set to X1 within BS 30. BS 30 isnow configured to use X1 for the sequence size in bits of the SEQ field322/344 for RLP data frames 320/340 received on the reverse link from MS10.

Next, at step 416, a determination is made within BS 30 as to whetherthe RETN/LAST field 310 of RLP control frame 300 is set to 0, i.e,whether Y1 has been assigned the value of 0. If RETN/LAST field 310 isset to 0, the process moves to step 420. At step 420, V₁ (retn)) is setto the default value for the maximum number of retransmission requestsfrom BS 30 for unreceived RLP data frames transmit from the MS 10 on thereverse link. In the embodiment of the invention, the default value maybe set to 0. The process next moves to step 424.

If however, at step 416, it is determined that RETN/LAST field 310 isnot set to 0, the process moves to step 418. At step 418 a determinationis made within BS 30 as to whether or not the value of Y1 in theRETN/LAST field 310 is a valid value. To be considered a valid value,the value of RETN/LAST field 310 should be a value within apredetermined range. In the embodiment of the invention thepredetermined range may be from 0 to 3. If the value of RETN/LAST field310 is not valid, the process moves to Block A, as described above, andthe synchronization procedure begins again. If, however, the value ofRETN/LAST field 310 is valid, the process moves to step 422. At step422, V1(retn) is set to Y1 within BS 30. BS 30 is now configured to useY1 for the maximum number of retransmission requests to be allowed fromBS 30 for unreceived RLP data frames transmitted from MS 10 on thereverse link.

Next, at base station executed step 424, a SYNC/ACK control frame(CTL=1111) is formatted with SES/FIRST field 308 set to the value of X2and, the RETN/LAST field 310 set to the value of Y2. At step 426, the BS30 transmits the SYNC/ACK control frame to the MS 10. Next, at step 428,a determination is made within MS 10 as to whether or not the SES/FIRSTfield 308 of SYNC/ACK control frame is set to 0, i.e, whether X2 hasbeen assigned the value of 0. If the SES/FIRST field 308 is set to 0,the process moves to step 432. At step 432, V2(ses) is set to thedefault value for the sequence size in bits of the SEQ field 322/344 tobe used on the forward link for RLP data frames. In the embodiment ofthe invention, the default value may be set to 8. The process next movesto step 436.

If however, at step 428, it is determined that SES/FIRST field 308 isnot set to 0, the process moves to step 430. At step 430, adetermination is made within MS 10 as to whether or not the value of X2in the SES/FIRST field 308 is a valid value. To be considered a validvalue, the value of SES/FIRST field 308 must be a value within thepredetermined range. In the embodiment of the invention, as for V1(ses),the predetermined range may be from 8 to 12. If the value of SES/FIRSTfield 308 is not valid, the process moves to Block B (in this caseequivalent to step 402) where the MS 10 sends a SYNC frame to the BS 30,thereby restarting the synchronization process. If however, the value ofSES/FIRST field 308 is valid, the process moves to step 434. At step434, V2(ses) is set to X2 within MS 10. MS 30 is now configured to useX2 for the sequence size in bits of the SEQ field 322/344 for RLP dataframes 320/340 received on the forward link from BS 30.

Next, at step 436, a determination is made within MS 10 as to whetherthe RETN/LAST field 310 of the SYNC/AK control frame is set to 0, i.e,whether Y2 has been assigned the value of 0. If the RETN/LAST field 310is set to 0, the process moves to step 440. At step 440, V₂ (retn)) isset to the default value for the maximum number of retransmissionrequests allowed from MS 10 for unreceived RLP data frames transmittedfrom BS 30 on the forward link. In the embodiment of the invention, thedefault value may be set to 0. The process next moves to step 444.

If however, at step 436, it is determined that RETN/LAST field 310 isnot set to 0, the process moves to step 438. At step 438, adetermination is made within MS 10 as to whether or not the value of Y2in the RETN/LAST field 310 is a valid value. To be considered a validvalue, the value of RETN/LAST field 310 must be a value within apredetermined range. In the embodiment of the invention, as forV2(retn), the predetermined range may be from 0 to 3. If the value ofRETN/LAST field .310 is not valid, the process moves to Block B, asdescribed above. If however, the value of RETN/LAST field 310 is valid,the process moves to step 442. At step 442, V2(retn) is set to Y2 withinMS 10. MS 10 is now configured to use Y2 for the maximum number ofretransmission requests to be allowed from MS 10 for unreceived RLP dataframes transmitted from BS 30 on the forward link.

Next, at step 444, an ACK control frame (CTL=1101) is formatted withSES/FIRST field 308 set to the value of X1 and the RETN/LAST field 310set to the value of Y1. At step 446, the MS 10 then transmits the ACKcontrol frame to BS 30. The ACK control frame serves as confirmationfrom MS 10 to BS 30 that the control frames required for configuring theRLP have been exchanged. At step 448, a determination is made within BS30 as to whether or not the SES/FIRST field 308 of the ACK control frame300 is set to X1 and whether or not the RETN/LAST field 310 is set toY1. If the SES/FIRST field 308 is set to X1 and the RETN/LAST field 310is set to Y1, the configuration is confirmed and the process moves tostep 450. At step 450 the configuration process ends, and datatransmission between MS 10 and BS 30 proceeds. RLP frames transmitted byMS 10 on the reverse link are received by BS 30 according to X1, andretransmission requests for those are transmitted by BS 30 according toY1. RLP frames transmitted by BS 30 on the forward link are received byMS 10 according to X2, and retransmission requests for those frames aretransmitted by MS 10 according to Y2.

Although described above with respect to certain programmableparameters. (i.e., the sequence number field and number ofretransmissions), it is within the scope of this invention to provideother programmable parameters. By example, the number of CRC check bitscan be made programmable and can be specified using the signallingdescribed above.

Thus, while the invention has been particularly shown and described withrespect to a preferred embodiment thereof, it will be understood bythose skilled in the art that changes in form and details may be madetherein without departing from the scope and spirit of the invention.

What is claimed is:
 1. A method for operating a first transceiver in atelecommunication system having a second transceiver, wherein said firsttransceiver and second transceiver communicate according to a variableparameter transmission protocol, said method comprising the stepsof:receiving a message from the second transceiver, said messageincluding control information, comprising a retransmission request valuespecifying a maximum number of retransmission requests to be transmittedfrom the first transceiver to the second transceiver requestingretransmission of at least one unreceived data frame of at least onedata frame transmitted to said first transceiving device from saidsecond transceiving device, said control information further comprisinginformation indicating a length of at least one sequence number fieldincluded in each said at least one data frame; receiving at least onereceived data frame of said at least one date frame; determining said atleast one unreceived data frame of said at least one data frame;determining if less than said retransmission request value ofretransmission requests has been transmitted for said at least oneunreceived data frame; and, if less than said retransmission requestvalue of retransmission requests has been transmitted, transmitting aretransmission request for said at least one unreceived data frame.
 2. Amethod for communicating between a first transceiving device and asecond transceiving device using a transmission protocol having at leastone variable parameter, said method comprising the steps of:transmittingfirst control information from the first transceiving device to thesecond transceiving device, said first control information comprisinginformation indicating a length of a first at least one variable lengthnondata field in a first at least one data frame and a firstretransmission requests allowed from said second transceiving device fordata frames transmitted from said first transceiving device that are notreceived at said second transceiving device; transmitting second controlinformation from the second transceiving device to the firsttransceiving device, said second control information comprisinginformation indicating a length of a second at least one variable lengthnondata field in a second at least one variable length nondata field ina second at least one data frame and a second transmission requestsvalue specifying a maximum number of retransmission requests allowedfrom said first transceiving device for data frames transmitted fromsaid second transceiving device that are not received at said firsttransceiving device; storing first control information in the secondtransceiving device and the second control information in the firsttransceiving device; and transmitting said first at least one data framefrom the first transceiving device to the second transceiving device inaccordance with said first control information and transmitting saidsecond at least one data frame from the second transceiving device tothe first transceiving device in accordance with said second controlinformation.
 3. The method of claim 2, wherein said step of transmittingsaid first at least one date frame comprises the steps of:receiving afirst plurality of data frames at said second transceiving device;detecting, at said second transceiving device, at least one unreceiveddata frame of said first plurality of data frames; determining if lessthan said first retransmission value of retransmission requests has beentransmitted for said at least one unreceived data frame of said firstplurality of data frames; and, in response to a positive determinationin said step of determining, transmitting a retransmission request fromsaid second transceiving device to said first transceiving device.
 4. Amethod for communicating between a first transceiving device and asecond transceiving device using a transmission protocol having at leastone variable parameter, said method comprising the steps of:transmittingfirst control information from the first transceiving device to thesecond transceiving device, said first control information comprising afirst retransmission value specifying a maximum number of retransmissionrequests allowed from said second transceiving device for data framestransmitted from said first transceiving device that are not received atsaid second transceiving device; transmitting second control informationfrom the second transceiving device to the first transceiving device,said second control information comprising a retransmission valuespecifying a maximum number of retransmission requests allowed from saidfirst transceiving device for data frames transmitted from said secondtransceiving device that not received at said first transceiving device;storing the first control information in the second transceiving deviceand the second control information in the first transceiving device; andsubsequently, transmitting a first plurality of data frames from thefirst transceiving device to the second transceiving device; receivingat least one received data frame of said first plurality of data framesat said second transceiving device; detecting, at said secondtransceiving device, at least one unreceived data frame of said firstplurality of data frames; determining if less than said firstretransmission value of retransmission requests has been transmitted forsaid at least one unreceived data frame of said first plurality of dataframes; and, in response to a positive determination in said step ofdetermining, transmitting a first retransmission request from saidsecond transceiving device to said first transceiving device.
 5. Themethod of claim 4, wherein said first control information furthercomprises information specifying a length of a first at least onevariable length nondata field in said first at least one data frame, andwherein said second control information further comprises informationindicating a length of a second at least one variable length nondatafield in said second at least one data frame.
 6. An apparatus foroperation in a first transceiver of a telecommunication system having asecond transceiver, wherein said first transceiver and secondtransceiver communicate according to a variable parameter transmissionprotocol, said apparatus comprising:a receiver for receiving a messagefrom the second transceiver, said message including control information,comprising a retransmission request value specifying a maximum number ofretransmission requests to be transmitted from the first transceiver tothe second transceiver requesting retransmission of at least oneunreceived data frame of at least one data frame transmitted to saidfirst transceiving device from said second transceiving device, saidcontrol information further comprising information indicating a lengthof at least one sequence number field included in each said at least onedata frame; a transmitter; a memory device; and a controller coupled tosaid receiver, said transmitter and said memory device, said controllerfor receiving said control information from said receiver according tosaid control information, storing said control information in saidmemory device, and processing said at least one data frame bydetermining at least one unreceived data frame of said at least one dataframe, determining if less than said retransmission request value ofretransmission requests has been transmitted for said at least oneunreceived data frame, and if less than said retransmission requestvalue of retransmission requests has been transmitted, initiatingtransmission of a retransmission request from said transmitter.
 7. Anapparatus for communicating between a first transceiving device and asecond transceiving device using a transmission protocol having at leastone variable parameter, said apparatus comprising:means for transmittingfirst control information from the first transceiving device to thesecond transceiving device, said first control information comprisinginformation indicating a length of a first at least one variable lengthnondata field in a first at least one data frame and a firstretransmission request value specifying a maximum number ofretransmission requests allowed from said second transceiving device fordata frames transmitted from said first transceiving device that are notreceived at said second transceiving device; means for transmittingsecond control information from the second transceiving device to thefirst transceiving device, said second control information comprisinginformation indicating a length of a second at least one variable lengthnondata field in a second at least one variable length nondata field ina second at least one data frame and a second transmission request valuespecifying a maximum number of retransmission requests allowed from saidfirst transceiving device for data frames transmitted from said secondtransceiving device that are not received at said first transceivingdevice; means for storing the first control information in the secondtransceiving device and means for storing the second control informationin the first transceiving device; means for transmitting said first atleast one data frame from the first transceiving device to the secondtransceiving device in accordance with said first control informationand means for transmitting said second at least one data frame from thesecond transceiving device to the first transceiving device inaccordance with said second control information.
 8. An apparatus forcommunicating between a first transceiving device and a secondtransceiving device using a transmission protocol having at least onevariable parameter, said apparatus comprising:means for transmittingfirst control information from the first transceiving device to thesecond transceiving device, said first control information comprising afirst retransmission value specifying a maximum number of retransmissionrequests allowed from said second transceiving device for data framestransmitted from said first transceiving device that are not received atsaid second transceiving device; means for transmitting second controlinformation from the second transceiving device to the firsttransceiving device, said second control information comprising aretransmission value specifying a maximum number of retransmissionrequests allowed from said first transceiving device for data framestransmitted from said second transceiving device that not received atsaid first transceiving device; means for storing the first controlinformation in the second transceiving device and means for storing thesecond control information in the first transceiving device; and meansfor transmitting a first plurality of data frames from the firsttransceiving device to the second transceiving device; means forreceiving at least one received data frame of said first plurality ofdata frames at said second transceiving device; means for detecting, atsaid second transceiving device, at least one unreceived data frame ofsaid first plurality of data frames; means for determining if less thansaid first retransmission value of retransmission requests has beentransmitted for said at least one unreceived data frame of said firstplurality of data frames; and means for transmitting a firstretransmission request from said second transceiving device to saidfirst transceiving device in response to a positive determination insaid means for determining.
 9. The apparatus of claim 7, wherein saidfirst control information further comprises information specifying alength of a first at least one variable length nondata field in saidfirst at least one data frame, and wherein said second controlinformation further comprises information indicating a length of asecond at least one variable length nondata field in said second atleast one data frame.
 10. The method of claim 8, wherein saidinformation further includes a retransmission request value specifying amaximum number of retransmission requests to be transmitted from saidfirst transceiver to said second transceiver requesting retransmissionof unreceived data frames of said at least one data frame, and whereinsaid step of processing further comprises the steps of determining atleast one unreceived data frame of said at least one data frame,determining if less than said retransmission request value ofretransmission requests has been transmitted for said at least oneunreceived data frame, and if less than said retransmission requestvalue of retransmission requests has been transmitted, initiatingtransmission of a retransmission request to the second transceiver fromsaid transmitter.